Method and apparatus for diagnosing CPU for CPU-runaway-preventing circuit

摘要

A method and apparatus for preventing runaway of CPU using a battery voltage as a power source voltage, in which the operation of CPU and the power source voltage of the CPU are inspected at the abnormal operation of the CPU and/or at the abnormal reduction of the power source voltage of CPU, system resetting is effected on the CPU, system reset signals for the CPU are counted. When the number of system reset signals for a predetermined time satisfies predetermined conditions, it is judged that the CPU is in failure. When the abnormal reduction of the power source voltage of the CPU is detected, the counting of system reset signals is prohibited.